Typically, an antenna device is known in which a matching circuit is installed for the purpose of achieving automatic matching of the input impedance of an antenna and the output impedance of a wireless unit. The antenna device further includes a generating circuit for generating a reference signal for the purpose of matching the impedances; and matches the impedance of the antenna based on the reference signal. As a result, when wireless communication based on transmit power control is being performed, the impedance matching can be performed in a stable manner.
However, in a conventional antenna device, while the impedance of the antenna is being matched, the wireless unit is separated from the antenna; the generating circuit is connected to the antenna. For that reason, during impedance matching, it is not possible to perform wireless communication.